Koch-backed group confirms financial ties to Cain campaign manager

A major conservative advocacy group, funded by Koch family oil interests, says it is reviewing its "financial dealings" with a Wisconsin charity headed by Herman Cain's campaign manager, raising fresh questions about the source of tens of thousands of dollars in funds that were used to pay expenses for Cain's presidential campaign.

The Center for Public Integrity reported late Thursday that Americans for Prosperity, one of the largest and most prominent of conservative political groups, has confirmed unspecified financial transactions with two closely linked Wisconsin non-profits -- Prosperity USA and Wisconsin Prosperity Network -- that were founded by Mark Block, Cain's campaign manager.

One of those groups, Prosperity USA, paid for $37,000 in expenses, including iPads, charter flights and items, for Cain's presidential campaign, according to financial documents disclosed this week by the Milwaukee-Wisconsin Journal Sentinel.

Non-profits are barred by law from paying for campaign expenses, and when the allegations first surfaced this week -- at the same time as the sexual harassment charges against the presidential candidate -- Cain said he would order an investigation of whether there were improper campaign violations.

Cain's campaign lawyer, Steve Bienek, declined to answer questions from NBC about the transactions between the Wisconsin charities headed by Block and the campaign, saying only that the campaign has retained an outside law firm to review them.

"We take these allegations very seriously," he said.

But the Center for Public Integrity report by Peter Stone raises additional questions as to whether Americans for Prosperity (AFP) funds were used by Block to pay Cain campaign expenses. AFP had "financial dealings with Prosperity USA and/or the Wisconsin Prosperity Network," Levi Russell, the spokesman for AFT is quoted as saying.

(Russell confirmed the transactions to NBC News, but declined to elaborate, and added that the group had no reason to believe there was any wrongdoing on its part.)

Some of those transactions are hinted at in the documents released by the Journal-Sentinel: They show a $5,000 expense in February 2011 for Cain to attend a meeting of a group called RightNation "at request of AFP" and that Block made a trip to Washington to meet with AFP's president Tim Phillips and David Koch."

Koch and his oil industry brother Charles Koch were the founders of Americans for Prosperity, but the group -- like most non-profits -- declines to identify its donors. The group is having a major conference in Washington starting Friday at which Cain and other presidential candidates are scheduled to speak.